A variety of braces, or orthoses, for feet and ankles are designed to apply force to a foot as the foot is forced against the ground under an individual's weight. This “ground reaction force,” when applied against a foot orthosis and, in turn, by the foot orthosis to a foot, causes the foot to conform to the orthosis, and may provide the foot with some support.
The “Arizona” brace is configured to stabilize the ankle and, more specifically, to non-operatively correct posterior tibialis tendon dysfunction (PTTD), or flatfoot, which may occur as the posterior tibial tending (PTT) collapses or otherwise changes in a way that renders it unable to support the longitudinal arch of the foot. An Arizona brace is typically a form fitted leather brace that resembles a boot, and is configured to surround the lower leg, ankle, hindfoot and midfoot. Although Arizona braces are effective, they are also typically stiff and uncomfortable; they preclude proper dorsiflexion (at heel strike) and/or plantarflexion (at toe off). Any arch support provided by an Arizona brace is typically only provided as a ground reaction force during mid-gait. Arizona braces are also quite bulky, making it difficult to fit them into normal shoes.
Other braces, such as the “Richie” brace, may be less bulky than the Arizona brace, and may enable some movement of the foot about the ankle while addressing PTTD or other disorders. In particular, Richie braces and other similar ankle braces often include hinges with axes that are configured to be aligned (or approximately aligned) with only a portion of the tibialtalor junction, or talocrural joint—the site about which movement of the foot relative to the lower leg occurs. Unfortunately, the manner in which foot and leg sections of a Richie brace pivot relative to one another does not accurately mimic the manner in which an individual's foot pivots relative to his or her leg. Furthermore, because a Richie brace typically includes a stiff footplate, as with the Arizona brace, a Richie brace typically only provides a meaningful amount of ground force at mid-gait.
Off the shelf and custom molded orthotics, which are commonly referred to as “shoe inserts,” only offer arch support when they have been inserted into shoes or other footwear. Even then, the primary arch support they provide is that resulting from ground reaction force as an individual walks.
A feature common to each of the foregoing orthoses is a somewhat stiff component that is configured to be placed under a majority of an individual's foot to provide arch support, via transfer of force from the ground, as the individual walks. The stiff materials transfer force from the ground and apply such force to the underside of the foot. Unfortunately, the stiff materials also impede flexibility and movement of the foot. They may also cause various foot muscles to atrophy. In some cases, in the absence of muscular activity, the foot may take on the shape of the orthosis. Instead of providing therapy or a solution to a foot or ankle disorder, orthoses that primarily provide arch support through ground reaction forces may actually exacerbate the problems and make the wearer ever more dependent on the orthosis.
Conventional soft bracing typically consists of flexible strapping, which allows the foot and ankle to move, but fails to provide adequate support for the medial column and/or the midfoot arch. Two reasons for this failure are (i) the limited amount of tension/force that can be applied with a flexible strap and (ii) the ease with which a soft brace collapses under a person's weight.